Compared to their representation in the 2019 US Census, most minority groups were overrepresented in clinical trials, while White individuals were underrepresented (eTable). The percentages of our findings on representation for race are as follows (US Census data are listed in parentheses for comparison5):
- White: 56.8% (72.5%)
- Black/African American: 28.3% (12.7%)
- Asian: 10.3% (5.5%)
- Multiracial: 1.1% (3.3%)
- Native Hawaiian or other Pacific Islander: 0.3% (0.2%)
- American Indian or Alaska Native: 0.2% (0.8%)
- Other: 0.5% (4.9%).
Our findings on representation for ethnicity are as follows (US Census data is listed in parentheses for comparison5):
- Hispanic or Latino: 21.4% (18.0%)
Although representation of Black/African American and Asian participants in clinical trials was higher than their representation in US Census data and representation of White participants was lower in clinical trials than their representation in census data, equal representation among all racial and ethnic groups is still lacking. A potential explanation for this finding might be that requirements for trial inclusion selected for more minority patients, given the propensity for greater severity of AD among those racial groups.2 Another explanation might be that efforts to include minority patients in clinical trials are improving.
There were great differences in ethnoracial representation in clinical trials when regions within the United States were compared. Based on census population data by region, the West had the highest percentage (29.9%) of Hispanic or Latino residents; however, this group represented only 11.7% of participants in AD clinical trials in that region.5
The South had the greatest number of participants in AD clinical trials of any region, which was consistent with research findings on an association between severity of AD and heat.6 With a warmer climate correlating with an increased incidence of AD, it is possible that more people are willing to participate in clinical trials in the South.
The Midwest was the only region in which region-specific clinical trials were not conducted. Recent studies have shown that individuals with AD who live in the Midwest have comparatively less access to health care associated with AD treatment and are more likely to visit an emergency department because of AD than individuals in any other US region.7 This discrepancy highlights the need for increased access to resources and clinical trials focused on the treatment of AD in the Midwest.
In 1993, the National Institutes of Health Revitalization Act established a federal legislative mandate to encourage inclusion of women and people of color in clinical trials.8 During the last 2 decades, there have been improvements in ethnoracial reporting. A 2020 global study found that 81.1% of randomized controlled trials (phases 2 and 3) of AD treatments reported ethnoracial data.3